PITTSBURGH (KDKA) — PennDOT is planning major construction on a busy bridge in Pittsburgh.

Inspectors say the Commercial Street Bridge is aging and needs to be replaced.

About 83,000 drivers a day depend on the Commercial Street Bridge. It is the connection between the Squirrel Hill Tunnel and Edgewood/Swissvale.

(Photo Credit: KDKA)

Completed in 1951 for $1.78 million dollars, the bridge is showing the impact of Pittsburgh winters.

“The bridge was designed for loads way less than it carries today,” said PennDOT Dist. 11 Executive Cheryl Moon-Sirianni. “The members are very slender and the members are failing.”

PennDOT plans to rebuild the bridge while maintaining two lanes of traffic in each direction.

Moon-Sirianni says the department’s consultant has come up with a couple of alternatives.

One would be to build the first two lanes north of the existing structure, move traffic over, demolish the old two lanes and build a replacement.

Once it’s done, the outbound traffic would be moved over to that span. The remainder of the old bridge would then be taken down.

Moon-Sirianni said that plan would take “about four to five years cause you’d have to do multiple phases.”

The alternative would to build all four lanes of a new bridge and slide them into place.

“You build the bridge next to the Parkway in Frick Park there and you would slide it onto the parkway,” Moon-Sirianni said.

All the supports for the new bridge would be built under the existing bridge while it is still carrying traffic.

That bridge replacement could be completed in 2 1/2 years at about the same costs.

However, Moon-Sirianni says it would mean a total closure of the Parkway East for “Probably what we’re looking at is about two weeks.”

PennDOT will finalize a plan in a couple of months, and then final engineering will begin and construction.

“We’re looking at about 2023 to start,” Moon-Sirianni said.

And once the new Commercial Street Bridge is finished, it will be time to rebuild the Frazier Street Bridge over Panther Hollow on the other side of the Squirrel Hill Tunnel.